A={$f:R\to R$}
with following properties
f has derivative of every order
$\forall x,y\in R$ $f(x+y)-f(y-x)=2xf'(y)$
then I have to find whole family
Till now I just able to show $f(x)-f(-x)/2x=2xf'(0)$
I wanted to solve this problem.
Please provide just hint..
Thanks in Advanced